JPH01292016A - Composition for gel coat and production of molded article therefrom - Google Patents

Abstract

PURPOSE:To obtain the title composition free from organic acid salt of cobalt, giving gel coat layer causing no yellowing or debonding, for use in bath tubs, etc., by incorporating a photopolymerization initiator and organic peroxide in a radically curing-type photocurable resin such as a unsaturated polyester resin. CONSTITUTION:The objective composition virtually free from organic acid salt by cobalt, by incorporating (A) a radically curing-type photocurable resin selected from unsaturated polyester resins and vinyl ester resins with (B) a photopolymerization initiator (e.g., 2-hydroxy-2-methyl-1-phenylpropane-1-one), and (C) an organic peroxide (pref. peroxy carbonate or peroxyester). This composition is used for the gel coat layer of molded articles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention mainly relates to the production of molded products that require aesthetic appeal, such as bathtubs, table tops, washstands, and the like.

[Conventional technology and issues]

Radical-curable resins, such as polyester resins and vinyl ester resins, can be cured by heating, but if this is attempted on an industrial scale, large heating equipment is required and costs are high, so they should be cured at the lowest possible temperature, preferably at the lowest possible temperature. There is a need for a method of curing at room temperature. However, in order to cure these curable resins at or near room temperature, an organic peroxide such as getone peroxide is used as a curing agent, and an organic acid salt of cobalt (naphthenate, naphthenate, etc.) is used as a curing accelerator. octylate) must be used in combination.

However, when cobalt naphthenate is used, for example, it has the undesirable drawback that molded products and coatings yellow over time.

For example, in the case of artificial marble, which is required to have an extremely light color, discoloration during use is not desirable because it greatly reduces its commercial value. In particular, since gel coat constitutes the surface layer of a resin molded article, discoloration of this layer must be avoided.

However, although the use of cobalt salts is undesirable in terms of yellowing of the resin,
Until now, effective room temperature or low temperature curing of resins has not been possible without the use of this material.

[Means and effects for solving the problem] The present inventors have made numerous attempts to avoid the use of cobalt salts, and have found that in order to avoid coloring during curing at room temperature, the use of peroxide-based curing agents has been found. The present invention was developed based on the finding that it is optimal to use a photocuring method without using an organic acid salt of cobalt as a curing accelerator.

Although the photocuring method was very effective in curing gel coats, other drawbacks were also discovered. When completely photocured, it exhibits sufficient physical properties as a gel coat.
Peeling easily occurred between the RPf7 layer or the cast layer. If you polish the gel coat to improve adhesion,
Although this drawback can be prevented, the number of man-hours increases significantly, which is disadvantageous in terms of productivity.

Therefore, in order to avoid this drawback, instead of completely curing in one light curing step, light curing should be used to advance the curing to an intermediate curing stage, and the final complete curing (cure) should be used.
discovered that the objective could be achieved by using an organic peroxide, and was able to complete the present invention.

Since the curing by light can be easily controlled, the curing of the gel coat or the subsequent 5-minute layer can be adjusted to the required degree. After the gel coat layer or, if necessary, the laminated portion is photocured, casting is performed using a radical curing resin containing a radical curing agent, and this is heated and cured together with the gel coat layer. As a result, the casting part and the gel coat part are cured and bonded together, and a strong molded product without peeling can be obtained. The heating temperature for curing is 100°C or less, preferably about 70 to 80°C.

As the resin for the gel coat, a radical curing resin is used which can be photocured and can also be cured with an organic peroxide. Examples include (1) unsaturated polyester resins (2) vinyl ester resins (epoxy acrylates).

(1) Unsaturated polyester resin contains α-β unsaturated polybasic acid or its acid anhydride as a necessary component, and is obtained by combining this with a saturated acid and esterifying it with a polyhydric alcohol. It is a form of polyester dissolved in a copolymerizable monomer such as styrene. For use in the present invention, the polyhydric alcohol component is preferably a component that imparts hot water resistance to the cured resin, such as neopentyl glycol, hydrogenated bisphenol A, or bisphenol A propylene oxide adduct, and the saturated acid is isophthalic acid, Terephthalic acid and the like are preferred.

If the gel coat layer is a resin with good hot water resistance, it will protect the surface of the molded product, so even a general-purpose resin can be used for casting.

(2) Vinyl ester resin is epoxy resin and (meth)
It is synthesized by the reaction of epoxy groups and carboxyl groups using acrylic acid.

As the epoxy resin, a bisphenol-glycidyl ether type resin having molecular positions 1350 to 700 is suitable.

In addition to (meth)acrylic acid, it is also practical to use polybasic acids or their acid anhydrides together.

The form utilized in the present invention is dissolved in a copolymerizable monomer such as styrene. Typically, the styrene monomer is used in an amount of 40 to 60% by weight, more typically about 50% by weight, based on the resin.

In order to make these radical curable resins photocurable as the gel coat resin of the present invention, it is necessary to use a photopolymerization initiator together. Various types of photopolymerization initiators can be used, but from the perspective of avoiding coloring of the cured gel coat layer, hydrogen abstraction types that use amines in combination are not suitable, and cleavage type radical generation sources are not suitable. good. For those examples.

(a) Acetophenone derivatives, such as 2-hydroxy-2-methyl-1 phenylpropan-1-one, Merck & Co., Ltd. "Daroeure 117"
(b) Benzyl ketals such as hydroxy-cyclohexyl-phenyl ketone (Ciba "Irgacure 184").

The gel coat resin of the present invention uses an organic peroxide in combination for final hardening. The type of organic peroxide used for this is not particularly specified, but in reality, the resin casting and heat curing operations to form the cast layer are performed at 100°C or below. Because there are many cases,
A type that decomposes at a relatively low temperature, for example, 80° C. or lower, is desirable.

As an example, the decomposition temperature is 1 to obtain a half-life of 10 hours.
Ketone peroxide, peroxyketal, peroxycarbonate, diacyl peroxide, below 20℃
Examples include peroxy esters. Among them, peroxycarbonates and peroxyesters are advantageous,
If appropriate curing temperature and handling safety are taken into account, bis(t-butylcyclohexyl) peroxydicarbonate (Kayaku Nouri Co., Ltd. “Parkyoku Dox #1”)
6°°) is appropriate. Combination use with other peroxides is also possible.

The resin used for the casting layer can be appropriately selected from general radical curing types, including the resins mentioned above. The surface properties of the molded article, such as hue, gloss, and water resistance, largely depend on the properties of the gel coat layer, so these aspects are rarely required of the resin for the casting layer. Rather, the casting resin is selected from the viewpoints of curing properties, adhesion to the gel coat layer, dimensional stability, mechanical strength, and the like.

When casting and curing the resin, a filler is usually used in combination with the casting resin to provide a suitable degree of transparency and to prevent cracks caused by heat generation during curing and molding.

Glass powder, aluminum hydroxide, etc. are commonly used as fillers.

In the composition and method of the present invention, it is of course possible to use a coloring agent, a mold release agent, a thixotropy imparting agent, a thermoplastic polymer, etc. in combination, if necessary.

Next, in order to further explain the present invention, Examples are shown below.

Example 1 (Vinyl ester resin for gel coat and casting (A)
(Manufacturing) In a 11 separable flask equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, epoxidized J1175 bisphenol liquid resin (Yuka Shell Epoxy Co., Ltd. Epicoat 827) was added as an epoxy resin to 360FI,
Prepare 75g of isophthalic acid and reduce to 170-19 in nitrogen stream.
After reacting at 0°C for 3 hours, the temperature was lowered to 135°C, and 0.3 g of hydroquinone, 86 g of methacrylic acid, 0.5 g of trimethylbenzylammonium chloride, and 1.52 g of chromium naphthenate were added, and the mixture was heated to 130-135 g in a nitrogen stream.
After reacting at ℃ for 3 hours, 100g of styrene was added and the reaction was further continued at 115-120℃ for 1 hour, resulting in an acid value of 9.1.
It became. At this stage, 380 g of styrene was further added to synthesize vinyl ester resin for gel coat (A>).

This resin had a Hazen color number of 350 and a viscosity of 11.4 voids.

(Formation of gel coat layer) Add Erosil R to 100 parts by weight of vinyl ester resin (A).
5 parts of -200 were added and kneaded with a three-roll mill to impart prickly tropism.

100 parts of this resin was added with "D" manufactured by Merck & Co. as a photopolymerization initiator.
A gel coat of the present invention was prepared by adding 2 parts of ``Arocure $ 1173'' and 1 part of ``Parkyoku Dox #16'' manufactured by Kayaku Nouri Co., Ltd. as a thermosetting agent, and this was designated as a gel coat composition (1).

30cm x 30cm x 5n+m coated with mold release agent
0.5 m of gel coat composition (1) on a glass plate of
I applied it with a bar coater so that the paint surface was 100m thick, waited until the coated surface was uniform, and then irradiated it for about 15 minutes with a 250W sun lamp (manufactured by Stanley Electric Co., Ltd.) 30cm below.
The gel coat layer was cured to the extent that it was dry to the touch.

(Casting, heat curing) The obtained gel coat layer is on one side, and a separate layer with a thickness of 2+u
i. 10m of FRP layer using white colored glass mat
They were arranged at intervals of m. During this time, vinyl ester resin (A
) 100 copies, 200 frits manufactured by Nippon Ferro Co., Ltd.
1 part, 15 parts of styrene, and 1 part of "Parryoku Dox #16".
After adding 5 parts of the resin and kneading it uniformly, the resin was defoamed and cast, and then heated and cured together with the gel coat layer at 60° C. for 2 hours and at 80° C. for 4 hours.

When the mold was removed after curing, a molded product (1) with a transparent gel coat layer on the surface was obtained.

Comparative Example 1 0.1 part of cobalt naphthenate (6% Co) was further added to the gel coat composition (1) to form a gel coat (II).
Then, light irradiation, casting, and heat curing were carried out in the same manner as in Example 1.
A molded article (2) was obtained.

Comparative example 2 Photopolymerization initiator "Dar" from gel coat composition (1).

Remove the eure #11 fu 3" and use it as a gel coat (I[l), and coat the surface of the gel coat on the glass plate to a thickness of 10
It was covered with a 0 μm polyester film and heated and cured at 80° C. for 5 hours, and then the film was removed and cast and heat cured in the same manner as in Example 1 to obtain a molded article (3).

Cut each molded product into 15CIi x 15CI11 pieces with a diameter of 1
0C- circular opening on one side 411! Place it in a boiling resistance test container with the gel coat layer on the inside,
A boiling test was conducted at a temperature of 98-99°C. The results are shown in Table 1.

Note to Table 1 *The devitrification part was determined to be due to peeling of the gel coat layer and casting layer, and only molded product (1) was judged to have no practical problem.

Example 2 (Manufacture of polyester resin (B) for gel coat) 21 equipped with a stirrer, fractionation condenser, gas introduction pipe, and thermometer
In a Yotsuro flask, 240 g of hydrogenated bisphenol A,
Neopentyl gelcol 230g, purified isophthalic acid 2
After charging 49 g of maleic anhydride and esterifying it at 190 to 210°C in a nitrogen stream to give an acid value of 21.4, maleic anhydride 1
47 g was added, and esterification was continued at the same temperature until the acid value reached 37.7. Then, the temperature was lowered to 140°C, and 0.15 g of hydroquinone and 650 g of styrene were added to produce a homogeneous solution, producing polyester resin (B) for gel coat. did. This resin had a Hazen color number of 100 and a viscosity of 8.4 poise.

(Formation of gel coat layer) Add Erosil R-20 to 100 parts of polyester resin (B).
After adding 2 parts of 0 and kneading to impart thixotropic properties, 100 parts of this resin was added with I of Ciba as a photopolymerization initiator.
Add 2 parts of rgacure #181'' and 2 parts of NOF Corporation's ``Percure 0'' (t-butyl peroxy 2-ethylhexanate) as a peroxide to obtain a photocurable gel coat composition fM (1'l/). And so.

As in Example 1, on a glass plate treated with a mold release agent,
A photocurable gel coat was applied to a thickness of 0.6 nu and irradiated for 20 minutes at 30 cII under the same sun lamp as in Example 1, and the surface of the gel coat became non-adhesive.

(Casting, heat curing) As a casting resin using isophthalic acid as a modified acid, 100 parts of "Revolac 2156" manufactured by Showa Kobunshi Co., Ltd., 10 parts of styrene, 200 parts of frit, and "Barriki Dox #1" were used.
6" was added, defoamed and injected between the FRP layer colored white on one side, and heated at 50°C for 2 hours and at 60°C for 2 hours.
Curing was completed by heating at 0° C. for 2 hours.

When this molded article was cut and subjected to a boiling test in the same manner as in Example 1, no yellowing of the gel coat layer was observed even after 500 hours.

Comparative Example 4 Photocurable gel coat composition obtained in Example 2 (IV)
When casting and heat-curing the gel coat composition (V) containing 0.1 part of cobalt naphthenate (6% Co) in the same manner as in Example 2, after boiling for 250 hours, heat-cure in a circular shape. Obvious yellowing occurred in the areas that came into contact with water.

Example 3 The photocurable gel coat composition (1) used in Example 1 was applied to a mold, and a similarly photocured gel coat layer and Fr(P
In between, the casting polyester resin used in Example 2 was injected, and a molded product was obtained under the same conditions as in Example 2.

This was subjected to a boiling test in the same manner as in Example 1, but no yellowing of the gel coat layer was observed even after 500 hours of boiling.

Comparative Example 5 A gel coat composition obtained by removing "Barryoku Dox #16" from the gel coat composition (1) of Example 1 and adding only a photopolymerization initiator was designated as a gel coat composition (Vl).

This was placed on a glass plate treated with a mold release agent in the same manner as in Example 1.
．． The film was coated to a thickness of 51 mm, and first irradiated with light under the same conditions as in Example 1 to obtain a coating that was dry to the touch.
m was passed at a rate of 2 m/min, and this was repeated twice to complete photocuring. Furthermore, a lining was cast in the same manner as in Example 1, and after heating and curing, the molded product was subjected to a boiling test. Partial devitrification was observed after 250 hours had elapsed, and the product had no commercial value. Ta.

〔Effect of the invention〕

As described above, the present invention provides a resin composition in which a photopolymerization initiator and an organic peroxide as a thermosetting agent are blended into a radical curable resin, and the resin composition does not substantially contain an organic acid salt of cobalt as a curing accelerator. Since the product is made into a gel coat layer and the backing layer is cast and heat cured without completely photo-curing the gel coat layer, it is possible to obtain an excellent molded product without yellowing or peeling of the gel coat layer. .

Claims (3)

[Claims] (1) (a) A photocurable radical curing resin selected from unsaturated polyester resins or vinyl ester resins, (b) a photopolymerization initiator (c) an organic peroxide, and cobalt. A composition for gel coating which is substantially free of organic acid salts of. (2) (a) A photocurable radical curing resin selected from unsaturated polyester resins or vinyl ester resins, (b) a photopolymerization initiator (c) an organic peroxide, and cobalt. A method for producing a molded article, which comprises using a composition substantially free of organic acid salts in a gel coat layer of the molded article. (3) Apply the gel coat to the mold, irradiate it with light to cure the gel coat to the desired degree of hardening, and then pour the resin to the required thickness with or without backing with glass fiber. The method for producing a molded article according to claim 2, which comprises heating and curing the post-gel coat layer and the casting layer.